Various oral dosage forms have been developed over the years for pharmaceuticals and dietary supplements. Among the more popular oral dosage forms are tablets, capsules and, most recently, gelcaps. Tablets are compressed or molded solid dosage forms of any size or shape. Solid, generally oblong-shaped tablets may sometimes be referred to as caplets. Tablets remain popular with consumers, however uncoated tablets suffer from drawbacks such as medicinal taste, a tendency to powder or flake (i.e., physical disintegration) when packaged in bottles, and/or the perception by consumers that they are not easy to swallow. These limitations are eliminated by coating the tablets with a polymeric coating.
During most of the 20th century, hard gelatin capsules were a popular dosage form for prescription and over-the-counter (OTC) drugs. Capsules are hard shell compartments made of two halves, including a body and a cap, wherein the cap partially and snugly overlaps with the body to enclose a dosable drug ingredient therein. The enclosed dosable ingredient is most often is a powder, liquid, paste or similar non-solid form.
Generally, empty hard shell capsules are produced by a conventional dip-molding process such as that which is described on page 182 of “Pharmaceutical Dosage Forms and Drug Delivery Systems, 7th Ed.”, (1999) by Howard C. Ansel, Loyd V. Allen Jr., and Nicholas G. Popovich, published by Lippincott Williams & Wilkins, Baltimore, Md. Consumers have found that such capsules are aesthetically pleasing, easy to swallow and mask the medicine taste of the drug contained therein. In addition, the bodies and caps of such capsules are often produced in different colors, resulting in a bi-colored capsule product having enhanced aesthetic appeal, as well as improved product identification and brand recognition by consumers. Many patients preferred capsules over coated or uncoated tablets, prompting pharmaceutical manufacturers to market certain products in capsule form even when they were also available in tablet form. However, due to potential tampering concerns, capsules are no longer a preferred delivery choice for consumer (i.e., over-the-counter) pharmaceuticals.
One alternative to capsule products are caplets, which are solid, oblong tablets that are often coated with various polymers such as cellulose ethers to improve their aesthetics, stability, and swallowability. Typically, such polymers are applied to the tablets either from solution in organic solvents, or from aqueous dispersion via spraying. Still other methods involve spray coating tablets with a gelatin coating solution. See, e.g., U.S. Pat. Nos. 4,973,480 and 6,113,945. However, such spray-coated tablets lack the glossy surface and elegance of the hard gelatin capsules. Additionally, it is not commercially feasible to spray-coat a tablet with a different color coating on each end.
Another alternative to capsule products are “gelcaps,” which are elegant, consumer-preferred dosage forms comprising solid tablets covered with a glossy gelatinous coating. Currently, gelcaps are among the most popular oral dosage forms. Several methods of producing gelcaps have been developed in an effort to provide tamper-proof capsule-like products. One category of such methods involve dipping tablets, one half at a time, into gelatin coating solutions, which can be of two different colors, see, e.g., U.S. Pat. No. 4,820,524, or dipping tablets of a first color halfway into a into gelatin coating solution of a second color, see, e.g., U.S. Pat. No. 6,113,945. Another category of such methods involves shrink-fitting the capsule halves onto a tablet form. See, for example, U.S. Pat. Nos. 5,415,868, 6,126,767, 5,464,631, 5,460,824, 5,317,849, 5,511,361, 5,609,010, 5,795,588 and 6,080,426, and International Patent Appln. Publication No. WO 97/37629. Another method involves sealing the body and cap of the capsule at the overlapping seam therebetween. See U.S. Pat. No. 5,824,338. Another method of producing gelcaps is via an enrobing process wherein two separate films made of gelatinous material are applied to opposite sides of a tablet by a pair of rotary dies. A detailed description of this process is provided, for example, in U.S. Pat. Nos. 5,146,730 and 5,459,983, and the entire contents and disclosures of both of these patents are hereby incorporated herein by reference.
Briefly, in the aforesaid rotary die process, two circular dies each having a circumferential surface are positioned such that the surfaces are in abutting relationship with one another, thereby forming a nip therebetween. Each of the dies have a series of matching recesses on their circumferential surfaces. As the dies rotate, the films are joined and fused together, at the nip between the dies where a pair of matching recesses form a pocket into which a tablet is dropped by a metered feed mechanism. As the dies continue to rotate, the tablet urges the films into the interior of the recesses in the dies, and the tablet is thereby securely enveloped and enrobed by the films, while the films continue to be joined and fused together about the tablet by the dies. Simultaneously with the fusing of the films about the tablet, the enrobed tablet is pinch-cut from the films by the rotary dies, whereupon it separates from the films in the form of an individual enrobed tablet. If the films used are of two different colors, the resulting enrobed tablets are bi-colored having a color transition line that is commensurate with the seam between the films. Thus, while foregoing process produces tamper-proof bi-colored enrobed tablets, the color transition of such products will always be commensurate with the seam between the films.
Each of the foregoing methods for producing tamper-proof coated tablets suffer from several shortcomings, including uneven color of the capsule halves and/or coatings, uneven thickness of the capsule halves and/or coatings, and the creation of raised seams between capsule halves and/or coatings. In addition, the bi-colored products resulting from the aforesaid methods have a line defined by the color transition, which is always the same as the line defined by the seam between the capsule halves and/or coatings.
U.S. Pat. No. 5,672,300 discloses the production and use of striped and patterned films with the foregoing rotary die process to produce patterned enrobed tablets. The striped films disclosed therein are produced by depositing stock film forming material of a first color from a first spreader box to form a base film and then, using a second spreader box, adding stripes of a differently colored stock material onto the base film. Films having different patterns, including stripes and/or marbleized, are created by oscillating the second spreader box relative to the first spreader box. The gelcaps produced by this process have multiple stripes, or a marbleized pattern, rather than simply being bi-colored (i.e., one half being one color and the other half being a second color). Films prepared by this process suffer from the limitation of having multiple layers, with increased total film thickness in the area where the second film material is applied. The increased film thickness creates an uneven appearance and feel to the surface, and retards dissolution, which is undesirable for immediate release dosage forms. Thus, there is still a need to produce bi-colored enrobed tablets that are enrobed with films according to the rotary die process and that have color transitions that are not commensurate with the seam between the films.